In a notebook personal computer (hereinafter, referred to as “note PC” for simply), which is a typical example of a portable or mobile type electronic device, a lithium ion rechargeable battery is generally used. In recent years, a number of battery pack-related fire accidents has been reported, and safety guidelines have been released for safe use of lithium ion batteries by cooperation of BAJ (The Battery Association of Japan) and JEITA (Japan Electronics and Information Technology Industries Association). Safety guidelines may be available from time to time on the associations home pages on the Internet.